The administration of blood or blood components often plays a critical role in the emergency and/or long term treatment of patients. Blood or the individual components of blood (such as platelets, plasma, red blood cells, etc.) may be administered or transfused to patients to treat a variety of conditions. For example, blood may be administered to a patient to replace blood lost as a result of trauma, while individual blood components may be administered as part of a longer term treatment of patients suffering from cancer or certain blood related diseases. The blood or blood components administered to the patient come from blood previously collected from donors. Blood collection from donors is usually performed at a local hospital, a blood collection center or even a community center such as a local school or church as part of a blood collection drive.
One of the most common blood collection techniques, and perhaps the most well-known, is the "manual" collection of whole blood from healthy donors. As commonly understood and as used herein, "manual" collection refers to a collection method where whole blood is allowed to drain from the donor and into a collection container without the use of external pumps or similar devices. This is in contrast to the so-called "automated" procedures where blood is drawn from a donor and is pumped and, if desired, further processed by an instrument or device.
Regardless of whether the blood collection technique is manual or automated, withdrawing blood from the donor typically includes inserting a needle into the donor's arm (and, more specifically, the donor's vein) and withdrawing blood from the donor through the needle. The "venipuncture" needle typically has attached to it one end of a plastic tube that provides a flow path for the blood. The other end of the plastic tube terminates in one or more preattached plastic blood containers or bags for collecting the blood. In the manual technique, the collection container and plastic tubing may also include a volume of a liquid anticoagulant, while in the automated technique, a separate container of anticoagulant may be provided. The anticoagulant is metered into the flow path (from the anticoagulant container) where it is mixed with the incoming whole blood. In any event, anticoagulant is required because of the tendency of blood to clot and adhere to the walls of the plastic surfaces which it contacts.
After collection but prior to transfusion to a patient, the blood is typically tested for pathogens such as virus, bacteria and/or other foreign substances. Typically, testing of the collected blood requires obtaining a sample of the blood from the blood donor at or near the time of collection. One well-known technique of obtaining a blood sample is to simply withdraw or collect the blood remaining in the flow path of the disposable set after donation. This involves removing the needle from the donor, inserting the needle into a vacuum sealed sampling vial and allowing the blood from the flow path to drain into the vial. However, because there is a limited supply of blood remaining in the flow path, there may not be enough blood to provide enough of a sample to perform all of the required or desired testing. Accordingly, if a larger volume or numerous samples of blood are required, the technician obtaining the sample may continue draining the blood from the tubing, eventually withdrawing the collected anticoagulated blood from the collection container. Using blood from the container for sampling may be less desirable in that the blood has been diluted with anticoagulant. Dilution of the blood can cause errors in or at least interfere with the accuracy of certain tests. In addition, withdrawing blood from the container also reduces the volume of blood in the container.
An alternative to collecting anticoagulated blood from the collection container is to clamp off the flow path near the collection container and divert the blood being withdrawn from the donor to a collection (sampling) vial or container. This procedure typically employs a particular type of disposable tubing set having a preattached sampling site on the main flow path. Blood at or near the sampling site may be obtained by piercing the sampling site with a separately provided needle or other piercing device which may have a sampling vial attached thereto.
An example of such a sampling method and system is described in U.S. Pat. No. 5,620,008 assigned to Migada, Inc. of Englewood Cliffs, N.J. That patent describes a blood sampling unit attached to a fluid flow path and a separately provided fluid coupling device adapted to engage the sampling unit. The fluid coupling device includes a sleeve with a double-ended needle disposed within the sleeve. One end of the needle is used to pierce the sampling unit while the other end of the needle is used to pierce a sampling container or vial.
Another way of obtaining a fluid sample is described in U.S. Pat. No. 5,167,656. That patent, which is assigned to the assignee of the present application, describes a disposable tubing set wherein the flow path includes an enlarged sample collection portion. Blood for sampling is collected in the enlarged portion by clamping off the flow path near the collection container and allowing the enlarged tubing portion to fill with blood. Once the desired volume of blood for sampling is collected in the enlarged tubing portion, the needle is removed from the donor and the blood is transferred to a vial by piercing the cap of the vial with the needle and allowing the blood to drain into the sampling vial.
While the above-described methods have worked satisfactorily, further improvements in sampling sterility, safety and accuracy are desirable. For example, it would be desirable to provide a sampling system in which the needle used to withdraw blood from the flow path is never exposed to the outside environment and is, therefore, less susceptible to contamination by the outside environment or accidental needle puncture of the user. It would also be desirable to provide a sampling system wherein the possibility of collecting any residual anticoagulant that may be present at or near the site (which could result in dilutional errors) is substantially eliminated. Thus, it would be desirable to provide a sampling system in which (1) the needle or piercing member can be advanced into the flow path of the blood and/or (2) "dead spaces" where anticoagulant can accumulate or insufficiently anticoagulated blood components collect and clot are substantially avoided. It would also be desirable to provide a sampling system in which transfer of blood does not require removal of the venipuncture needle and reinsertion of the needle (into the vial), but instead permits the blood to flow directly from the donor to the sampling vial. It would also be desirable to provide a sampling system which is integrated with the blood collection set and requires few separate or external components.